Rectifier and method of making the same



April 29, 1947. M. F. SKINKER ET AL, 2,419,602

RECTIFIER AND METHOD OF MAKING THE SAME Filed Aug. 14, 1945 2Sheets-Sheet 1 IN VEN TORS ATTORNEY April 1947- M. F. SKINKER ET AL2,419,602

' RECTIFIER AND METHOD OF MAKING THE SAME Filed Aug. 14, 1943 2Sheets-Sheet 2 IN V EN TORS t. as, new

?atented RECTIFIER AND METHOD OF MAKING THE SAME Murray F. Skinker,Montclair, and Leslie B. Haigh, West Orange, N. J assignors to.FederalTelephone and Radio Corporation, Newark, N. J a corporation of DelawareApplication August 14, 1943, Serial No. 498,65

9 Claims.

This invention relates to improvements in rectifiers and methods ofmaking the same, and more particularly to rectifiers of the dry contacttype, such as selenium rectifiers.

An object of this invention is directed to the provision of improved,small, low-capacity rectifiers.

Another object of this invention is to provide a small rectifier ofsimple design and high effl-' ciency.

A further object of this invention is directed toward an improved andsimplified method of making rectifiers.

Generally speaking, this invention may be defined as comprising theconstructions and combinations recited in the annexed claims andillustrated in certain embodiments in the drawings accompanying andforming a part of this application, wherein:

Fig. 1 is a longitudinal cross-sectional view of a preferred form ofrectifier construction in accordance with the present invention;

Fig. 2 is a top plan view of the rectifier illustrated in Fig. 1;

Fig. 3 is a horizontal cross-sectional view taken along the line 3-3 ofFig. 1;

Fig. 4 is a longitudinal cross-sectional view of a modified rectifierconstruction;

Fig. 5 is a transverse cross-sectional view taken along line 5-5 of Fig.4;

Fig. 6 is a perspective view of the finished rectifier illustrated inFig. 4;

Fig. 7 is a longitudinal cross-sectional view of still another form ofrectifier;

Fig. 8 is a transverse cross-sectional view taken along the line 8-8 ofFig. 7; and

Fig. 9 is a perspective view of the completed rectifier illustrated inFig. 7.

In the first form of invention shown in Figs. 1, 2 and 3, it will beseen that the rectifier is builtup on a metal base plate I0 having araised portion l2, preferably substantially centrally located withrespect to the plate as a whole, upon which is formed in any suitablemanner known to the art, a thin selenium layer I4. A layer of insulationI6, which may be a thermoplastic artificial insulation such aspolystyrene or may be formed of insulating paper is placed on the baseIII and is provided with a through opening uncovering the selenium spotI4. Alead wire I8 is placed on the insulating layer I6, passing over theopening therethrough and a second layer of insulation 20 is applied overthe lead wire I8 and joining with the first insulating layer I6. Thesecond insulating layer is also provided with a through openingsubstantially aligned with they opening in the insulating layer I6.Counterelectrode alloy is then melted and poured through the alignedopenings forming contact with the selenium layer I4 and, at the sametime fusing with a portion of the lead wire I8 andthus holding thelatter in position. In accordance with the construction of the describedmodification, the base plate I0 is preferably formed with four ears 24at its corners and these are bent upwardly and over the top insulatinglayer 20 pressing the parts against the base plate III to form a unitarystructure. A second lead wire 26 may be soldered or otherwise attachedto the base plate I0.

It will be seen from the description just given that the describedconstruction provides a very simple and yet extremely efiicient lowcapacity rectifier. The selenium spot and the counterelectrode area incontact therewith are kept small, thus providing for high currentdensity and improved efflciency of the rectifier. In the drawings, thethickness of the parts such as the metal plate III, selenium layer I4and the insulating layers I6 and 20' have been exaggerated for thepurposes of clear illustration, and while the invention is not intendedto be limited to any particular size, it may be mentioned thatrectifiers of the type described have been manufactured with a length Ofabout of an inch, a width of about A of an inch and a thickness of lessthan A; of an inch. Additionally, while the integral legs formed on thebase plate are shown to extend longitudinally thereof, it will beobvious to those skilled in this art that these built-up and turnedoverlegs could project laterally from the base plate as well. After assemblyor the exposed portions of the rectifier, including the base plate. theturned-over legs, the counter-electrode alloy and parts of the leadwires can be further insulated as by painting, if desired.

In the second form of this invention, illustrated in Figs. 4, 5 and 6, abase plate III] has placed thereon a selenium layer II4 which, in turn,is covered by a layer of insulation IIB having a small central openingleading to the selenium layer beneath. The base plate selenium layer andinsulating layer may then be surrounded by an insulating tube I20, forexample, a small piece of spaghetti which also may be provided with anopening I'2I substantially aligned with the opening in the insulatinglayer I I6. Lead wire I I8 is longitudinally looped around one side ofthe insulating tube I20 so that a portionthereof between the insulatinglayer H6 and tube I20 passes over the hole above inginthe insulatinglayer iii tomake contact with the selenium layer ill. The lead wire Illis thus firmly connected with the counterelectrode alloy, the loop aboutthe tube i2l merely to take the strain oil! the connection with thecounter-electrode alloy and hold the insulating tube I20 in place. Asecond'lead wire I28 may be attached to'the metal plate Ill and thistube, and may be longitudinally looped about the tubing to form astronger and more permanent lead connection. After the counterelectrodealloy has been melted through the opening Hi, the latter may be closedby melting on or otherwise applying a small mass or strip of insulationiii. In Figs. 4 and 5 the relative thicknesses of the insulating layers,the selenium layer and the metal plate have been exaggerated for thesake of clarity. Actually, the resulting rectifier-structure may havesomewhat the proportions as shown in Fig. 6 which is approximately fourtimes the size of rectifiers of this type which have been constructed.

Figs. 7, 8 and 9 illustrate the most simplified form of rectifier inaccordance with the present invention. Again, a layer of selenium 2 isapplied to one side of a metal base plate 2H! and a layer of insulatingmaterial 2 i 6 which may be, for example, masking tape, is placed overthe selenium plate. The insulating layer 2 has a central openingtherethrough, and a lead wire thereof, it is to be clearb understoodthat this description is made only by way oi. example and not as alimitation on the scope of our invention.

aisafis forth in the objects and the accompanying c For claimsspecifically directed'to the form of the invention shown in Figs. 1 to3, reference is to be made to co-pending application No. 720,035, filedJanuary 3, 1947, in the name of Leslie 3. Haigh, one of the-jointapplicants named herein.

We claim:

1. A rectifier comprising, in combination, a metallic base plate, alayer of seleniinn on said base plate, a layer of insulating material onsaid selenium layer, and having a small opening therethrough exposing aportion of the selenium layer, counter-electrode alloy extending throughsaid opening to contact said selenium, a lead wire fused to saidcounter-electrode alloy, and a second continuous insulating layerextending about said base plate, selenium layer, first insulating layerand lead wire.

V 2. The combination according to claim 1, in combination with a secondlead wire attached to said base plate and surrounded by said secondinsulating layer. a

3. A rectifier comprising, in combination, a metallic base plate, alayer of selenium on said base plate, a layer of insulation on saidselenium, hav- 2l l is placed upon this insulating layer with a portionthereof extending over the opening. Counter-electrode alloy 222 ismelded through the opening in the insulating layer against the seleniumlayer 2 on the one hand and fusing with a. portion of the lead wire 2l8on the other hand. A second lead wire 226 is soldered or otherwiseattached to the lower side of the metal base plate 2l0. The parts arethen sprayed, dipped or otherwise painted in an insulating paint to forma small integral rectifier unit. This insulation not only performs itsexternal insulating function but also assists in attaching the leadwires to the unit and holding them in place.

Again for the purposes of illustration, the thichiesses of the plate andthe selenium and insulating layers have been exaggerated in Figs. 7 and8, while the entire rectifier unit as it will actually appear but drawnto about four times actual size is illustrated in Fig. 9.

Various changes and modifications coming within the scope of the presentinvention will occur to those skilled in this art. The base plate Illwill preferably consist of a metal containing iron but other metalssuitable for use with selenium for the purposes of rectification may beused, or the base plate in may be formed of any metal coated with aniron-containing alloy. The manner in which the selenium'is applied tothe base plate is of no particular importance with respect to thepresent invention and various methods known to the art may be utilized,while after assembly, the rectifier may be electroformed in the usualmanner to create the desired barrier layer. As previously pointed out,the insulating layers can be any suitable insulation, either artificialresinous insulating materials or plain ing an opening therethroughexposing a portion of the selenium, an insulating tube surounding saidbase plate, selenium and insulating layer, and having anopening'therethrough substantially aligned with the opening in saidinsulating layer, counter-electrode alloy extending through said twoopenings to the selenium layer, and a lead wire extending between saidinsulating layer and said insulating tube and fused in said alloy.

4. The combination according to claim 3, in combination with furtherinsulating material covering the opening in said insulating tube,

5. The combination according to claim 3, in combination with a secondlead wire attached to said base plate and extending between said baseplate and said insulating tube.

6. The combination according to claim 3, in which said lead wire is inthe form of a closed loop extending longitudinally inside and outside ofsaid insulating tube, and in which the inner portion of the loop isfused to said counter-electrode alloy.

7. The combination according to claim 3, in which said lead wire is inthe form of a closed loop extending longitudinally inside and outside ofsaid insulating tube, and in which the inner portion of the loop isfused to said counter-electrode alloy, in combination with a second leadwire in the form of a closed loop extending longitudinally inside andoutside of said insulating or impregnated paper. In the form ofinvention illustrated in Figs. 1, 2 and 8, the selenium may be appliedover the entire base plate, as in the other forms illustrated, insteadof on a raised Spot.

first loop and attached to said base Plate.

8. A rectifier comprising, in combination, a metallic base plate, alayer of selenium on said base plate, a layer of insulation on saidselenium, having an opening therethrough exposing a portion of theselenium layer, counter-electrode alloy extending-through said openingto said selenium, a first lead wire attached to said counter-electrodealloy, a second lead wire attached to said base plate, and a continuousinsulating layer enclosing said base plate, selenium layer, the

' 5 layer oi insulation, the counter-electrode alloy, and the attachedportions of said lead wires.

9. The method of making a rectifier which includes the steps of forminga selenium layer on a metal base plate, covering the selenium layer withan insulating layer having an opening therethrough, meltingcounter-electrode alloy through said opening against said seleniumlayer,

attaching a lead wire to the counter-electrode alloy, attaching a secondlead wire to the base plate, and painting the exposed portions 0! thebase plate, selenium layer, insulating layer, the counter-electrodealloy and the connected portions of the lead wire with a continuousinsulatins coating. v

I MURRAY F. SKINKER.

LESLIE B. HAIGH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

